External magnetic field arrangement scheme optimization design method for improving working performance of proton exchange membrane fuel cell

Abstract

An external magnetic field arrangement scheme optimization design method for improving the working performance of a proton exchange membrane fuel cell comprises the following steps: (1) building a proton exchange membrane fuel cell three-dimensional model, importing the model into finite element analysis software, and building a hydrogen fuel cell-free and porous medium flow-magnetic field coupled multi-physical field model; (2) applying a permanent magnet outside the proton exchange membrane fuel cell to introduce a magnetic field, and changing conditions such as the external magnetic field intensity, the permanent magnet arrangement mode and the permanent magnet height; (3) acquiring fluid pressure distribution cloud charts in the cathode and anode runners of the proton exchange membrane fuel cell and a power curve of the fuel cell under different magnetic field conditions; and (4) analyzing the fluid pressure distribution cloud picture and the power curve in the step (3), and determining the most reasonable external magnetic field arrangement scheme for improving the working performance of the proton exchange membrane fuel cell. According to the invention, the permanent magnets are applied outside the proton exchange membrane fuel cell to introduce a magnetic field, and the arrangement scheme of the permanent magnets is optimized.

Description

Technical Field

[0001] The present invention relates to the field of proton exchange membrane fuel cells, and in particular to an optimization design method for an external magnetic field arrangement scheme for improving the working performance of a proton exchange membrane fuel cell. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) is an advanced clean energy technology that uses hydrogen and oxygen for electrochemical reactions to directly convert chemical energy into electrical energy, and produces water as the only byproduct. It is of great significance to alleviate the energy crisis and protect the ecological environment, and has broad application prospects in transportation, aerospace, portable power, military and marine fields. At present, PEMFC technology still faces many challenges, including high catalyst material costs, limited service life and low power density. The power density of fuel cells directly reflects the quality of their performance, so improving their power density is considered one of the most important technical goals.

[0003] During the operation of PEMFC, the diffusion of gas in the porous diffusion layer inside the fuel cell directly affects the output power of the battery. The amount of gas diffusion entering the catalyst layer per unit time can be increased by increasing the pressure in the flow channel, controlling the fluid flow rate, or applying exhaust side back pressure. Since oxygen and hydrogen are paramagnetic and diamagnetic gases, respectively, a magnetic gradient force will be generated in a magnetic field environment, intensifying the convection and diffusion between molecules. Introducing a magnetic field by applying a permanent magnet outside the PEMFC can promote the movement of gas inside the battery and effectively improve the output power of the battery. The magnetic field strength, layout and height of the permanent magnet will affect the flow of fluid inside the battery, thereby affecting the working performance of the PEMFC.

[0004] Patent CN112397737A discloses a stack device and a manufacturing method of a platinum-based magnetic field-controlled fuel cell, which specifically includes the following steps: S1: preparing a platinum-based magnetic multi-element nanoparticle catalyst coated on a proton exchange membrane; S2: preparing a single fuel cell based on a platinum-based magnetic multi-element nanoparticle catalyst; S3: connecting multiple single fuel cells prepared in S2 in series to form a stack, and using a DC electromagnet to provide an adjustable magnetic field. A DC power supply with an adjustable external current is used to supply a DC electromagnet with different magnetic fields to improve the performance of its platinum-based magnetic multi-element nanoparticle catalyst, thereby improving the performance of the fuel cell. However, this method changes the structure of the surface of the proton exchange membrane, which may change the performance parameters of the membrane. The steps for preparing the platinum-based magnetic multi-element nanoparticles and catalysts are cumbersome and costly, which is not conducive to large-scale production. If the stack is operated for a long time, the device consumes a lot of energy; during the operation of the fuel cell, the complex chemical composition of the platinum-based magnetic catalyst may pollute the internal working environment of the battery, reducing the reliability of the fuel cell operation.

[0005] Patent CN113851686A discloses a hydrogen fuel cell stack device based on magnetic field regulation, characterized in that the hydrogen fuel cell stack is formed by stacking a number of single hydrogen fuel cells in series and horizontally, and can be movably adjusted and placed in a solenoid; according to the placement direction of the positive and negative electrodes of the stack in the solenoid, the area where the hydrogen fuel cell stack is located in the solenoid during operation is adjusted, and the intensity and gradient direction of the magnetic field generated in different areas inside the solenoid are controlled by an external adjustable current source, so that the output power of the hydrogen fuel cell stack can be regulated. However, when acting on a hydrogen fuel cell stack with a large number of single cell stacks and a large volume, the length and winding diameter of the solenoid required by the device will be greatly increased, the structure is not compact, and the required layout space is large. In addition, the solenoid provides current through an external current source to generate a magnetic field, so the consumed electric energy will increase with the increase of the working time of the stack, which is not conducive to energy saving and has low safety.

[0006] Therefore, in order to fully realize the improvement of PEMFC working performance by magnetic field, it is an urgent problem to study a magnetic field layout scheme that is safe, energy-saving, compact and can greatly improve battery performance. Summary of the invention

[0007] In view of the existing technical deficiencies, the purpose of the present invention is to provide an optimization design method for the arrangement of an external magnetic field to improve the working performance of a proton exchange membrane fuel cell.

[0008] The technical solution adopted by the present invention is:

[0009] A method for optimizing the arrangement of an external magnetic field for improving the working performance of a proton exchange membrane fuel cell comprises the following steps:

[0010] Step 1: Build a three-dimensional model of a proton exchange membrane fuel cell and import it into the finite element analysis software to establish a multi-physics field model of hydrogen fuel cell-free and porous medium flow-magnetic field coupling;

[0011] Step 2: introducing a magnetic field by applying a permanent magnet outside the proton exchange membrane fuel cell, and changing conditions such as the strength of the applied magnetic field, the arrangement of the permanent magnet, and the height of the permanent magnet;

[0012] Step 3: Obtain the fluid pressure distribution cloud diagram in the cathode and anode flow channels of the proton exchange membrane fuel cell under different magnetic field conditions and the power curve of the fuel cell;

[0013] Step 4: Analyze the fluid pressure distribution cloud map and power curve of step 3 to determine the most reasonable external magnetic field arrangement scheme to improve the working performance of the proton exchange membrane fuel cell.

[0014] Furthermore, the three-dimensional geometric model of the proton exchange membrane fuel cell described in step 1 includes an anode side bipolar plate, an anode side gas diffusion layer, an anode side catalyst layer, a proton exchange membrane, a cathode side catalyst layer, a cathode side gas diffusion layer and a cathode side bipolar plate, and ribs are provided on the cathode side bipolar plate and the anode side bipolar plate, and the groove area between adjacent ribs of the cathode side bipolar plate is an air flow channel, and the groove area between adjacent ribs of the anode side bipolar plate is a hydrogen flow channel, and the air flow channel and the hydrogen flow channel are connected to the cathode side gas diffusion layer and the anode side gas diffusion layer respectively.

[0015] Furthermore, when establishing the magnetic field coupling model in step 1, the volume force of the magnetic fluid under the magnetic field needs to be added.

[0016]

[0017] where f k is the volume force, μ0 is the vacuum magnetic permeability, which is 4π×10 -7 H / m, M is the magnetization intensity of the magnetic material, H is the magnetic field intensity, is a vector differential operator.

[0018] Furthermore, the conditions changed in step 2 specifically include:

[0019] The strength of the external magnetic field H is used to change the volume force on hydrogen and oxygen;

[0020] The permanent magnet arrangement includes three situations: bipolar arrangement, anode arrangement and cathode arrangement;

[0021] The height of the permanent magnet, h, is used to change the magnetic field to cover the effective reaction area inside the battery.

[0022] Furthermore, the step 3 specifically includes:

[0023] Step 3.1: For different permanent magnet arrangements, different external magnetic field intensities H are set, and in the three-dimensional model of the proton exchange membrane fuel cell established in step 1, the middle position of one of the cathode flow channel or the anode flow channel and the depth direction of the flow channel are selected as the research path, and the numerical simulation method is used to calculate and obtain the fluid pressure distribution cloud map and power curve of the section where the research path is located under different external magnetic field intensities H for different permanent magnet arrangements;

[0024] Step 3.2: Set different permanent magnet heights h, and select the middle position of one of the cathode flow channel or anode flow channel in the three-dimensional model of the proton exchange membrane fuel cell established in step 1 and along the depth direction of the flow channel as the research path, and use the numerical simulation method to calculate and obtain the fluid pressure distribution cloud map and power curve under different permanent magnet heights h in the section where the research path is located.

[0025] Furthermore, the step 4 specifically includes:

[0026] According to the power curves obtained in step 3.1 for different permanent magnet arrangements under different external magnetic field intensities H, the magnetic field intensity corresponding to the curve with large power density peak and average power density under the same permanent magnet arrangement is selected as the optimal range of the external magnetic field intensity, and the permanent magnet arrangement corresponding to the curve with large power density under the same external magnetic field intensity and the same current density is selected as the optimal arrangement form of the permanent magnet;

[0027] According to the fluid pressure distribution cloud diagrams obtained in step 3.1 for different permanent magnet arrangements and different external magnetic field strengths H, the influence of the permanent magnet arrangement and the external magnetic field strength H on the fluid transmission in the flow channel is analyzed from a microscopic perspective;

[0028] According to the power curves at different permanent magnet heights h obtained in step 3.2, the permanent magnet height corresponding to the curve with the largest power density at the same current density is selected as the optimal range of permanent magnet height;

[0029] According to the fluid pressure distribution cloud diagram under different permanent magnet heights h obtained in step 3.2, the influence of the permanent magnet height h on the fluid transmission in the flow channel is analyzed from a microscopic perspective.

[0030] The beneficial effects of the present invention are:

[0031] The present invention provides an optimization design method for an external magnetic field arrangement scheme for improving the working performance of a proton exchange membrane fuel cell, which introduces a magnetic field by applying a permanent magnet outside the proton exchange membrane fuel cell, and changes the conditions such as the strength of the external magnetic field, the arrangement mode of the permanent magnet, and the height of the permanent magnet, and uses a numerical simulation method to obtain the fluid pressure distribution cloud map in the cathode and anode flow channels of the proton exchange membrane fuel cell under different magnetic field conditions and the power curve of the fuel cell, analyzes the influence of the external magnetic field on the working performance of the fuel cell, and determines the most reasonable magnetic field arrangement scheme to maximize the working performance of the proton exchange membrane fuel cell, with low implementation cost and high safety. At the same time, the introduction of the magnetic field improves the distribution of the fluid pressure inside the fuel cell, effectively promoting the transmission of the fluid in the flow channel and the electrochemical reaction of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of the present invention;

[0033] Figure 2 It is a structural schematic diagram of a three-dimensional model of a proton exchange membrane fuel cell constructed for simulation according to the present invention;

[0034] Figure 3 It is a structural schematic diagram of a three-dimensional simulation model of a proton exchange membrane fuel cell under different permanent magnet arrangement modes;

[0035] Figure 4 It is a structural schematic diagram of a three-dimensional simulation model of a proton exchange membrane fuel cell at different permanent magnet heights;

[0036] Figure 5 It is the power curve of applying different magnetic field strength H under the condition of bipolar arrangement of permanent magnets of the same height;

[0037] Figure 6 It is the power curve of applying different magnetic field strength H when the anode is arranged with permanent magnets of the same height;

[0038] Figure 7 It is the power curve of applying different magnetic field strength H when the cathode is arranged with permanent magnets of the same height;

[0039] Figure 8 It is the fluid pressure distribution cloud diagram when no permanent magnet is arranged;

[0040] Fig. 9 It is the fluid pressure distribution cloud diagram under the condition of bipolar arrangement of permanent magnets with the same height and different magnetic field strengths H;

[0041] Fig.10 It is the fluid pressure distribution cloud diagram under the condition of permanent magnets with the same height at the anode and different magnetic field strengths H;

[0042] Fig.11It is the fluid pressure distribution cloud diagram with different magnetic field strengths H applied when the cathode is equipped with permanent magnets of the same height;

[0043] Fig.12 It is the power curve of applying different permanent magnet heights h when the cathode is arranged with a permanent magnet with a magnetic field strength of 0.35T;

[0044] Fig.13 It is a nephogram of fluid pressure distribution when a permanent magnet with a magnetic field strength of 0.35T is arranged at the cathode and different permanent magnet heights h are applied.

[0045] Reference numerals

[0046] 1. Anode side bipolar plate; 2. Anode side gas diffusion layer; 3. Anode side catalyst layer; 4. Proton exchange membrane; 5. Cathode side catalyst layer; 6. Cathode side gas diffusion layer; 7. Cathode side bipolar plate; 8. Ribs; 9. Air flow channel; 10. Hydrogen flow channel; 11. Permanent magnet. DETAILED DESCRIPTION

[0047] To facilitate understanding of the present invention, the technical solution of the present invention will be further described below through the accompanying drawings and embodiments. The present invention is not limited to the specific embodiments described herein and can be implemented through different design solutions.

[0048] Unless otherwise specified, technical or scientific terms used in the present invention shall have the same meanings as commonly understood by persons of ordinary skill in the art.

[0049] The present invention is described in detail below with reference to the accompanying drawings.

[0050] Reference Figure 1 This embodiment provides a method for optimizing the arrangement of an external magnetic field for improving the performance of a proton exchange membrane fuel cell, comprising the following steps:

[0051] Step 1: Build a three-dimensional model of a proton exchange membrane fuel cell, import the three-dimensional model of the proton exchange membrane fuel cell into the COMSOL Multiphysic finite element analysis software, and establish a multi-physics field model based on hydrogen fuel cell-free and porous medium flow-magnetic field coupling.

[0052] like Figure 2As shown, the three-dimensional geometric model of the proton exchange membrane fuel cell constructed in step 1 includes an anode side bipolar plate 1, an anode side gas diffusion layer 2, an anode side catalyst layer 3, a proton exchange membrane 4, a cathode side catalyst layer 5, a cathode side gas diffusion layer 6 and a cathode side bipolar plate 7. Both the cathode side bipolar plate 7 and the anode side bipolar plate 1 are provided with ribs 8, the groove area between adjacent ribs of the cathode side bipolar plate 7 is an air flow channel 9, and the groove area between adjacent ribs of the anode side bipolar plate 1 is a hydrogen flow channel 10. The air flow channel 9 and the hydrogen flow channel 10 are connected to the cathode side gas diffusion layer 6 and the anode side gas diffusion layer 2 respectively. Air and hydrogen enter the air flow channel 9 and the hydrogen flow channel 10 through the external air intake pipes of the cathode side bipolar plate 7 and the anode side bipolar plate 1, respectively, and are distributed to the catalyst layer and the proton exchange membrane 4 through the gas diffusion layer to react. The cathode side bipolar plate 7 and the anode side bipolar plate 1 both use a straight channel flow field design with the same structure and size, and the fluid flow area is 50×50mm 2 The ribs 8 are all long rectangular ribs with a height of 0.4 mm and a width of 0.2 mm. The widths of the air flow channel 7 and the hydrogen flow channel 8 are both 0.95 mm.

[0053] When establishing the magnetic field coupling model in step 1, it is necessary to add the volume force of the magnetic fluid under the magnetic field.

[0054]

[0055] where f k is the volume force, μ0 is the vacuum magnetic permeability, which is 4π×10 -7 H / m, M is the magnetization intensity of the magnetic material, H is the magnetic field intensity, is a vector differential operator.

[0056] Step 2: introducing a magnetic field by applying a permanent magnet outside the proton exchange membrane fuel cell, and changing conditions such as the strength of the external magnetic field, the arrangement of the permanent magnets, and the height of the permanent magnets; the conditions changed in step 2 specifically include:

[0057] The strength of the external magnetic field H is used to change the volume force on hydrogen and oxygen;

[0058] The permanent magnet arrangement includes three situations: bipolar arrangement, anode arrangement and cathode arrangement;

[0059] The height of the permanent magnet, h, is used to change the magnetic field to cover the effective reaction area inside the battery.

[0060] like Figure 3 As shown, the changed arrangement of the external permanent magnets in step 2 includes arranging permanent magnets 11 at the center positions of the outer sides of the bipolar, anode and cathode of the three-dimensional model of the proton exchange membrane fuel cell.

[0061] like Figure 4 As shown, the height h of the external permanent magnet changed in step 2 is to use different permanent magnet height dimensions under the specifications of a permanent magnet length of 50 mm and a width of 10 mm.

[0062] Step 3: Obtain the fluid pressure distribution cloud diagram in the cathode and anode flow channels of the proton exchange membrane fuel cell under different magnetic field conditions and the power curve of the fuel cell.

[0063] The step 3 specifically includes:

[0064] Step 3.1: For different permanent magnet arrangements, different external magnetic field intensities H are set, and in the three-dimensional model of the proton exchange membrane fuel cell established in step 1, the middle position of one of the cathode flow channel or the anode flow channel and the depth direction of the flow channel are selected as the research path, and the numerical simulation method is used to calculate and obtain the fluid pressure distribution cloud map and power curve of the section where the research path is located under different external magnetic field intensities H for different permanent magnet arrangements;

[0065] Step 3.2: Set different permanent magnet heights h, and select the middle position of one of the cathode flow channel or anode flow channel in the three-dimensional model of the proton exchange membrane fuel cell established in step 1 and along the depth direction of the flow channel as the research path, and use the numerical simulation method to calculate and obtain the fluid pressure distribution cloud map and power curve under different permanent magnet heights h in the section where the research path is located.

[0066] Step 4: Analyze the fluid pressure distribution cloud map and power curve of step 3 to determine the most reasonable external magnetic field arrangement scheme to improve the working performance of the proton exchange membrane fuel cell.

[0067] In order to better describe the power curve in step 3, the concepts of peak power density and average power density are introduced. The peak power density refers to the point with the highest power on the power curve; the peak power density refers to the point with the highest power on the power curve. 2 The average of the four power density values ​​in the current density interval is taken as the average power density in the high current density area.

[0068] The step 4 specifically includes:

[0069] Step 4.1: According to the power curves obtained in step 3.1 for different permanent magnet arrangements under different external magnetic field intensities H, the magnetic field intensity corresponding to the curve with large power density peak and average power density under the same permanent magnet arrangement is selected as the optimal range of the external magnetic field intensity, and the permanent magnet arrangement corresponding to the curve with large power density under the same external magnetic field intensity and the same current density is selected as the optimal arrangement form of the permanent magnet;

[0070] Step 4.2: According to the fluid pressure distribution cloud diagrams obtained in step 31 under different external magnetic field strengths H for different permanent magnet arrangements, the influence of the permanent magnet arrangement and the external magnetic field strength H on the fluid transmission in the flow channel is analyzed from a microscopic perspective;

[0071] Step 4.3: According to the power curves at different permanent magnet heights h obtained in step 3.2, the permanent magnet height corresponding to the curve with a large power density at the same current density is selected as the optimal range of the permanent magnet height;

[0072] Step 4.4: Based on the fluid pressure distribution cloud diagram at different permanent magnet heights h obtained in step 3.2, analyze the effect of the permanent magnet height h on the fluid transmission in the flow channel from a microscopic perspective.

[0073] In this embodiment, when determining the optimal range of the applied magnetic field strength and the optimal arrangement of the permanent magnets, H is set to be 0-0.4T, and the height of the permanent magnet is set to be 40mm. The power curves of different magnetic field strengths H under different permanent magnet arrangements are as follows: Figure 5-7 shown. Figure 5 This is the power curve in the case of bipolar arrangement. The peak power density of the battery is 0.4398W / cm 2 The maximum value is increased to 0.5662W / cm at a field strength of 0.35T 2 , the increase is 28.7%; the average power density is 0.4133W / cm 2 The maximum increase is 0.5478W / cm 2 , an increase of 32.5%. Figure 6 This is the power curve under the anode arrangement. The peak power density of the battery is increased to 0.6002W / cm at a field strength of 0.35T. 2 , the increase is 36.5%; the average power density is increased to 0.5666W / cm 2 , an increase of 37.1%. Figure 7 This is the power curve under the cathode arrangement. The peak power density of the battery is increased to 0.6281W / cm at a field strength of 0.35T. 2 , the increase is 42.8%; the average power density is increased to 0.5981W / cm 2 , the increase was 44.7%. Figure 5-7It can be seen that no matter which permanent magnet arrangement is used, when the magnetic field strength increases from 0.35T to 0.4T, the power curve shows a downward trend, indicating that the greater the external magnetic field strength is, the more conducive to the improvement of battery performance. Therefore, the optimal range of the external magnetic field strength is 0.3T to 0.4T, and the preferred magnetic field strength is 0.35T. When permanent magnets with a magnetic field strength of 0.35T are arranged at the bipolar, anode and cathode of the fuel cell, the peak power density increases by 28.7%, 36.5% and 42.8% respectively, and the average power density increases by 32.5%, 37.1% and 44.7% respectively. Therefore, the best permanent magnet arrangement is the cathode arrangement.

[0074] In this embodiment, Figure 8 The following is a cloud diagram of fluid pressure distribution without magnetic field. It can be seen that the maximum and minimum pressures of the cathode and anode fluids are at the inlet and outlet of the flow channel respectively, and the pressure gradually decreases as the fluid flows. This phenomenon is mainly attributed to the resistance encountered by the fluid in the flow channel, which reduces the fluid velocity and leads to a decrease in fluid pressure. Fig. 9 This is a fluid pressure distribution cloud map with different magnetic field strengths H applied in a bipolar arrangement. In the cloud map, the fluid pressure in the flow channel presents a negative value, indicating that the volume force in this area is small. Conversely, in the area where the fluid pressure presents a positive value, the volume force is large. Due to the diamagnetic nature of hydrogen and the paramagnetic nature of oxygen, applying a magnetic field to both poles of the battery at the same time will cause the reaction area to be affected by both the anode and cathode magnetic fields. In this way, the magnetic field gradient at a certain point in the reaction area is simultaneously affected by the combined effect of the two magnetic poles, resulting in a weakened magnetic field gradient. The volume force on hydrogen in the vortex-shaped area increases, while the volume force on oxygen decreases. Fig.10 This is a cloud diagram of fluid pressure distribution when different magnetic field intensities H are applied under the anode arrangement. Due to the reverse magnetic properties of hydrogen, the minimum pressure value of hydrogen at the anode is biased towards the place with higher gradient magnetic field density. The volume force in this area is relatively small. At the same time, the hydrogen pressure near the inlet and outlet of the anode flow channel is mostly positive, indicating that the volume force is relatively large, which is not conducive to the full transmission of hydrogen. Fig.11 The fluid pressure distribution cloud diagram of different magnetic field strengths H under the cathode arrangement. The hydrogen pressure near the inlet and outlet of the anode flow channel is mostly negative, and the hydrogen pressure in the middle area is more positive, which is more conducive to the full transmission of hydrogen; at the cathode, due to the paramagnetism of oxygen, the pressure in the middle part of the flow channel with low magnetic field density is low, which is conducive to the flow of oxygen. In summary, applying a magnetic field to the cathode of the fuel cell is more conducive to the transmission and reaction of hydrogen and oxygen, and its effect is the best. Figure 9-11 , under the three conditions of 0.3T, 0.35T and 0.4T magnetic field strength, when the magnetic field strength of 0.35T is applied, the pressure increase in the cathode and anode flow channels is the largest.

[0075] In this embodiment, when determining the optimal range of the permanent magnet height h, because the magnetic field formed by the permanent magnet is a gradient magnetic field, the height of the selected magnet should not exceed the effective reaction size inside the battery, and h is set to 20mm, 30mm, 40mm and 50mm. The arrangement of the external permanent magnet is set to cathode arrangement, and the magnetic field strength is 0.35T. The power curves of different permanent magnet heights h are as follows: Fig.12 As shown. When the height of the permanent magnet is 40mm, the working performance of the fuel cell is improved the most, and its power density peak and average power density are increased by 42.8% and 44.7% respectively. When the height of the permanent magnet is less than 40mm, the performance of the battery will also improve as the height of the magnet increases, but when the height of the permanent magnet is 50mm, which is the same as the flow field length of the fuel cell bipolar plate, the working performance of the battery decreases to a certain extent. Compared with the permanent magnet height of 40mm, the peak power density and average power density of the battery are reduced by 33.4% and 31.8% respectively. It can be seen that when the height of the permanent magnet is 40mm, the effect of improving the performance of the fuel cell is best.

[0076] In this embodiment, a 0.35T magnetic field strength is applied to the cathode of the fuel cell, and the fluid pressure distribution cloud diagrams with permanent magnet heights of 30mm, 40mm and 50mm are as follows: Fig.12 As shown. When the magnet height is 30mm, the inlet and outlet on the anode side are the areas with the highest maximum pressure, which is not conducive to hydrogen transmission; when the magnet height is 40mm, the pressure values ​​on the anode and cathode sides are the largest, and the positive pressure area of ​​hydrogen on the anode side is larger than when the magnet height is 30mm, which is conducive to hydrogen transmission and reaction; when the magnet height is 50mm, the area of ​​the positive pressure area of ​​hydrogen on the anode side is larger than the other two cases, but the positive pressure area of ​​oxygen on the cathode side is very small, and the positive pressure area is at the outlet, which is not conducive to the reduction reaction on the cathode side. In summary, a magnet height of 40mm is more conducive to improving the performance of the fuel cell.

[0077] Based on the analysis of the numerical simulation results in this embodiment, the most reasonable external magnetic field arrangement scheme for improving the working performance of the proton exchange membrane fuel cell is determined as follows:

[0078] The optimal value range of the applied magnetic field strength H is 0.3-0.4T, preferably 0.35T;

[0079] The best arrangement of permanent magnets is cathode arrangement;

[0080] The optimum height h of the permanent magnet is 40 mm.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and do not limit it. The present invention is not limited to the above examples. Any modifications, additions or equivalent substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing the arrangement of an external magnetic field for improving the performance of a proton exchange membrane fuel cell, characterized in that: The following steps are involved: Step 1: Build a three-dimensional model of a proton exchange membrane fuel cell and import it into the finite element analysis software to establish a multi-physics field model of hydrogen fuel cell-free and porous medium flow-magnetic field coupling; Step 2: introducing a magnetic field by applying a permanent magnet outside the proton exchange membrane fuel cell, and changing conditions such as the strength of the applied magnetic field, the arrangement of the permanent magnet, and the height of the permanent magnet; Step 3: Obtain the fluid pressure distribution cloud diagram in the cathode and anode flow channels of the proton exchange membrane fuel cell under different magnetic field conditions and the power curve of the fuel cell; Step 4: Analyze the fluid pressure distribution cloud map and power curve of step 3 to determine the most reasonable external magnetic field arrangement scheme to improve the working performance of the proton exchange membrane fuel cell.

2. The method for optimizing the arrangement of an external magnetic field for improving the performance of a proton exchange membrane fuel cell according to claim 1, characterized in that: In step 1, the three-dimensional geometric model of the proton exchange membrane fuel cell includes an anode side bipolar plate, an anode side gas diffusion layer, an anode side catalyst layer, a proton exchange membrane, a cathode side catalyst layer, a cathode side gas diffusion layer and a cathode side bipolar plate, the cathode side bipolar plate and the anode side bipolar plate are both provided with ribs, the groove area between adjacent ribs of the cathode side bipolar plate is an air flow channel, the groove area between adjacent ribs of the anode side bipolar plate is a hydrogen flow channel, and the air flow channel and the hydrogen flow channel are connected to the cathode side gas diffusion layer and the anode side gas diffusion layer respectively.

3. The method for optimizing the arrangement of an external magnetic field for improving the performance of a proton exchange membrane fuel cell according to claim 1, characterized in that: In step 1, when establishing the magnetic field coupling model, the volume force of the magnetic fluid under the magnetic field needs to be added. where f k is the volume force, μ0 is the vacuum magnetic permeability, which is 4π×10 -7 H / m, M is the magnetization intensity of the magnetic material, H is the magnetic field intensity, is a vector differential operator.

4. The method for optimizing the arrangement of an external magnetic field for improving the performance of a proton exchange membrane fuel cell according to claim 1, characterized in that: The conditions changed in step 2 specifically include: The strength of the external magnetic field H is used to change the volume force on hydrogen and oxygen; The permanent magnet arrangement includes three situations: bipolar arrangement, anode arrangement and cathode arrangement; The height of the permanent magnet, h, is used to change the magnetic field to cover the effective reaction area inside the battery.

5. The method for optimizing the arrangement of an external magnetic field for improving the performance of a proton exchange membrane fuel cell according to claim 1, characterized in that: The step 3 specifically includes: Step 3.1: For different permanent magnet arrangements, different external magnetic field intensities H are set, and in the three-dimensional model of the proton exchange membrane fuel cell established in step 1, the middle position of one of the cathode flow channel or the anode flow channel and the depth direction of the flow channel are selected as the research path, and the numerical simulation method is used to calculate and obtain the fluid pressure distribution cloud map and power curve of the section where the research path is located under different external magnetic field intensities H for different permanent magnet arrangements; Step 3.2: Set different permanent magnet heights h, and select the middle position of one of the cathode flow channel or anode flow channel in the three-dimensional model of the proton exchange membrane fuel cell established in step 1 and along the depth direction of the flow channel as the research path, and use the numerical simulation method to calculate and obtain the fluid pressure distribution cloud map and power curve under different permanent magnet heights h in the section where the research path is located.

6. The method for optimizing the arrangement of an external magnetic field for improving the performance of a proton exchange membrane fuel cell according to claim 1, characterized in that: The step 4 specifically includes: Step 3.1: According to the power curves obtained in step 3.1 for different permanent magnet arrangements under different external magnetic field intensities H, the magnetic field intensity corresponding to the curve with large power density peak and average power density under the same permanent magnet arrangement is selected as the optimal range of the external magnetic field intensity, and the permanent magnet arrangement corresponding to the curve with large power density under the same external magnetic field intensity and the same current density is selected as the optimal arrangement form of the permanent magnet; Step 4.2: According to the fluid pressure distribution cloud diagrams obtained in step 3.1 for different permanent magnet arrangements and different external magnetic field strengths H, the influence of the permanent magnet arrangement and the external magnetic field strength H on the fluid transmission in the flow channel is analyzed from a microscopic perspective; Step 4.3: According to the power curves at different permanent magnet heights h obtained in step 3.2, the permanent magnet height corresponding to the curve with a large power density at the same current density is selected as the optimal range of the permanent magnet height; Step 4.4: Based on the fluid pressure distribution cloud diagram at different permanent magnet heights h obtained in step 3.2, analyze the effect of the permanent magnet height h on the fluid transmission in the flow channel from a microscopic perspective.

Images